U.S. Pat. No. 3,847,119, Hoffman et al, issued Nov. 12, 1974, is typical of a large number of references showing a transfer drum or roller for assisting in transfer of a toner image to a receiving sheet from a photoconductive image member. To prevent soiling of the reverse side of the transfer sheet, the transfer roller is continuously cleaned by a fur brush and the particles of toners so cleaned are removed by a vacuum source. See also, U.S. Pat. No. 4,026,648, Takahashi, issued May 31, 1977 showing a blade cleaner for a transfer roller.
U.S. Pat. No. 4,453,820, Suzuki, issued June 12, 1984 is representative of a number of references which show an intermediate transfer member to which a toner image is transferred from the original image member, and from which the toner image is then transferred directly to a receiving sheet. Unless transfer to the receiving sheet is 100% effective, the surface of such a transfer member must be cleaned before a new toner image is transferred to it. See also, Bothner, U.S. Pat. No. 4,712,906, issued Dec. 15, 1987.
U.S. Pat. No. 4,876,577, Ogura et al, issued Oct. 24, 1989 is representative of a number of references which show an image-forming unit into which a cartridge is loaded. The cartridge includes a photoconductive drum, a blade cleaning device for the drum, a charger and access to the drum for both toning and transfer of images. Including the cleaning device for the photoconductive as part of the cartridge eliminates the need for operator disposal of residual toner cleaned off the photoconductive drum. The residual toner left in the cartridge can be disposed of or recycled when the cartridge is returned to the factory for recycling of the photoconductive drum.
U.S. Pat. No. 4,862,224, granted to Ku, on Aug. 29, 1989, shows a roller cleaning device for a transfer drum. The cleaning roller is made of a material attractive to toner and is biased relative to the transfer drum to create an electric field attracting toner to the cleaning roller. The roller is articulatable in and out of contact with the transfer drum so that the apparatus can superpose a plurality of single color images on a receiving sheet carried by the transfer drum to make a multicolor image. A blade is spring-biased against the cleaning roller to clean toner off of the roller into a container associated with the roller. The container is either emptied or replaced periodically.